This application relates to and claims priority from Japanese Patent Application No. 11-24094 filed on Feb. 1, 1999, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates generally to heat exchangers, and particularly to a fin for a double heat exchanger including two or more heat exchangers such as a condenser and a radiator.
2. Related Art
Conventionally, a fin for a heat exchanger is formed into a corrugated shape having plural bent portions and plural flat portions each of which connects the adjacent bent portions. The fin has plural louvers formed by partially cutting and raising each flat portion to increase a heat transfer rate of the fin.
FIGS. 14 and 15A show such a fin for a double heat exchanger including a condenser and a radiator, which was studied by the inventors. The fin includes a condenser fin 512 and a radiator fin 612 integrally formed. A louver-forming processing amount defined by the number of the louvers, a width of each louver or an inclining angle of each louver of the condenser fin 512 is differently set from that of the radiator fin 612, so that each of the condenser and the radiator has an appropriate heat-exchange performance. In FIGS. 14 and 15A, the number of the louvers formed in the condenser fin 512 is smaller than that of the radiator fin 612.
However, as shown in FIGS. 15A-15C, since the louvers are formed by partially cutting and raising each flat portion, when the louver-forming processing amount of the radiator fin 612 is larger than that of the condenser fin 512, each bent portion of the radiator fin 612 may be deformed to have a smaller radius of curvature R than that of the condenser fin 512. As a result, as shown in FIG. 14, the whole fin may be deformed into a bow shape so that a radius of curvature of the fin at a side of the radiator fin 612 is decreased. A fin for a heat exchanger having a single heater core such as a condenser or a radiator may also be deformed due to the same reason.
In view of the foregoing problems, it is an object of the present invention to provide a fin for a heat exchanger which is restricted from being deformed.
According to the present invention, a corrugated fin for a heat exchanger having a plurality of tubes through which a fluid flows is disposed between adjacent tubes. The fin includes a plurality of bent portions, and a plurality of flat portions each connecting adjacent bent portions. Each of the flat portions has a louver formed by partially cutting and raising each of the flat portions, and includes a first flat portion and a second flat portion. A processing amount of the first flat portion for forming the louver is smaller than that of the second flat portion, and the first flat portion has a plastically deformed portion formed by plasticity processing.
Therefore, a whole processing amount of the first flat portion is increased by the plastically deformed portion, and becomes substantially equal to that of the second flat portion. As a result, the fin is restricted from being deformed.
Preferably, the plastically deformed portion is formed adjacent to the bent portions in the first flat portion. As a result, the fin is further restricted from being deformed.